The impact of an early loading dose of clopidogrel on the preprocedural Thrombolysis in Myocardial Infarction (TIMI) flow grade and the in-hospital outcomes for STEMI patients receiving primary PCI

Studies have yielded divergent results regarding the optimal timing of the clopidogrel loading dose, specifically whether it should be administered before or at the initiation of percutaneous coronary intervention. To date, there is limited data on how the timing of the clopidogrel loading dose affects the preprocedural thrombolysis in myocardial infarction (TIMI) flow grade and outcomes for patients with STEMI.

The objective of our study was to examine the effects of an early clopidogrel loading dose on preprocedural TIMI flow grade and in-hospital mortality among STEMI patients undergoing primary PCI.

We conducted an observational, prospective, single-center study involving 202 STEMI patients who underwent primary PCI. Data were gathered from November 2023 to March 2024. Patients were categorized based on the timing of the clopidogrel loading dose: at least two hours before the procedure (Early group) or in the catheterization laboratory during the procedure (Late group). The preprocedural TIMI flow grade was assessed in both groups. In-hospital mortality was compared between the groups and was considered the primary endpoint.

A total of 202 STEMI patients received primary PCI, with 85 patients (42.1%) in the Early group and 117 patients (57.9%) in the Late group. No significant differences were observed between the groups in terms of baseline demographic, clinical, and procedural characteristics.

A smaller percentage of patients in the early group exhibited preprocedural TIMI flow 0 compared to those with preprocedural TIMI flow 1-3 (34.4% vs 53.7%, p<0.01). Conversely, the late group showed a higher percentage of patients with preprocedural TIMI flow 0 compared to those with preprocedural TIMI flow 1-3 (65.5% vs 46.2%, p<0.01).

The mortality rate was observed to be lower in the Early group compared to the Late group; however, this difference was not statistically significant (4.9% vs 7.6%, p=0.39). Furthermore, late loading was not identified as an independent risk factor for in-hospital mortality, with a hazard ratio of HR= 1.02 and p=0.99. Nevertheless, the presence of preprocedural TIMI 0 flow emerged as a significant and independent predictive factor for in-hospital mortality, as indicated by the multivariate analysis [HR 12.1, 95%CI (4.23-34.40), p=0.004].

The administration of an early clopidogrel loading dose in STEMI patients undergoing primary PCI is linked to a lower incidence of preprocedural TIMI flow 0 and suggests a trend towards reduced mortality. Although the late loading dose did not serve as an independent risk factor for in-hospital mortality, the preprocedural TIMI flow 0 was established as an independent predictive factor for in-hospital mortality.